Mixing processes - Influence of the viscosity model on flow calculations

Distributive mixing plays an important role in polymer processing, especially for shear-sensitive materials. Many materials with very high filler contents or partly crosslinked materials show a rheological yield point, which makes mixing of such materials very difficult. Due to this fact it is very important to predict the mixing behavior before expensive mixing devices are manufactured or production stops due to insufficient product quality. Besides the mixing quality, both pressure drop and dissipative heating are important quality criteria for mixer geometries. The CARPOW equation presented in this paper is capable to describe the flow behavior of materials with a rheological yield point depending on the shear rate and temperature due to a combination of a Carreau equation and a power law. The implementation of this fluid model in the open source CFD toolbox Open-FOAM® and the combination with a particle tracking approach allow predicting the mixing behavior of such materials in distributive mixing dev...